Low flow irrigation emitters (also referred to as “drip emitters”) are generally known in the art for use in delivering irrigation water at relatively low volume flow rate, thereby conserving water. Such irrigation devices commonly comprise an emitter housing connected to a water supply tube through which irrigation water is supplied under pressure. The drip irrigation device taps a portion of the relatively high pressure irrigation water from the supply tube for flow through a typically long or small cross-section flow path in the device to achieve a desired pressure drop prior to discharge at a drip-like flow rate. In a conventional system, a large number of the drip irrigation devices are mounted at selected positions along the length of the supply tube to deliver the irrigation water to a large number of specific points, such as directly to a plurality of individual plants or other vegetation.
Drip emitters can be installed either below ground (“subsurface”) or above ground. Drip emitters, subsurface or above ground, provide numerous advantages over spray emitters located above ground. For example, subsurface emitters limit water loss due to runoff and evaporation which provides significant savings in water consumption. Further, drip emitters prevent the distribution of water to undesired terrain, such as roadways or walkways, created from “overspray.” In contrast, spray emitters often generate overspray that disturbs vehicles and/or pedestrians and wastes water. Water also may be used more economically by directing it at precise locations of the root systems of plants or other desired locations above or below ground. Another advantage of subsurface emitters is being able to water an area while still being able to use the area. For instance, such emitters may be used to irrigate park or school grounds at any desired time. Spray emitters located above ground, on the other hand, may be undesirable at parks and school grounds during daytime hours when children or other individuals are present.
A further benefit is that subsurface emitters are not easily vandalized, given their underground installation. Thus, subsurface emitters result in reduced costs associated with replacing vandalized equipment and with monitoring for the occurrence of such vandalism. This is important particularly for publicly accessible areas, such as parks, school grounds, and landscaping around commercial buildings and parking lots. The above-identified benefits and advantages are only illustrative of the many benefits and advantages of subsurface and above ground drip emitters.
One known challenge with drip emitters is the ability to provide one that compensates for water pressure fluctuations in a reliable manner to provide a consistent low flow or drip rate. Such fluctuations result in the inefficient and wasteful use of water. Thus, there is a need to provide for a relatively constant drip flow output from drip emitters, regardless of fluctuations in the water pressure in the supply tube, with an emitter design that is economic to manufacture.
Another known challenge with drip emitters is to provide a design that does not clog. Clogging of an emitter may result from the introduction of grit, debris, or other particulate matter, both from debris entering the emitter through the supply tube and debris entering the emitter from the terrain being irrigated, i.e., “back siphoning.” Such obstruction of an emitter may result in severe, and in some cases complete, flow restriction, potentially preventing the emitter from operating entirely. Many irrigation systems depend on the operation of each specifically situated emitter for sufficient water coverage to maintain healthy grass, crop, or other plant growth.
In the event that an emitter does become obstructed, there is a need for the emitter to be capable of self-flushing the obstruction. Without such ability, the emitter would have to be replaced or cleaned manually. Even more concerning is that the obstruction would not become apparent until the target of the emitter's water flow visibly suffered from lack of irrigation. This could result in the complete loss of the vegetation intended for irrigation. Accordingly, there is a need to prevent drip emitters from becoming obstructed.